C.10 Frame Titles

Each Emacs frame always has a title, which appears in window
decorations and icons as the name of the frame. The default title is
of the form ‘invocation-name@machine’ (if there is
only one frame) or shows the selected window's buffer name (if there
is more than one frame).

You can specify a non-default title for the initial Emacs frame with
a command line option:

‘-T title’

‘--title=title’

Specify title as the title for the initial Emacs frame.

The ‘--name’ option (see Resources) also specifies the title
for the initial Emacs frame.